Field of the Invention
The present invention relates to a light emitting diode package and, more particularly, to a high voltage light emitting diode package that may be operated under a high voltage.
Discussion of the Background
Light emitting devices equipped with light emitting diodes, for instance, light emitting diode packages, are widely used not only for applications such as pilot lamps, electronic scoreboards and displays due to its capability of realizing various colors, but also for regular lighting due to capability of realizing white light. Light emitting diodes are increasingly used in various fields due to advantageous features, such as high efficiency, long operational lifespan, and environmental friendliness.
A white light emitting device is generally composed of a combination of a blue light emitting diode and a yellow phosphor. However, since the white light emitting device composed of the combination of the blue light emitting diode and the yellow phosphor emits white light having high color temperature due to lack of a red color region, it is not suitable for regular lighting.
While a red phosphor may be also used to realize a warm white color having low color temperature, application of the red phosphor is limited due to low optical efficiency of the red phosphor. Further, phosphors react with moisture absorbed from the outside and experience efficiency deterioration over time, thereby reducing operational lifespan of the light emitting device and, in particular, the red phosphor experiences more rapid efficiency deterioration than a green or yellow phosphor, thereby further reducing operational lifespan of the light emitting device.
On the other hand, in order to apply the light emitting device to regular lighting using a household power source or the like, it is necessary to provide a light emitting diode package that can be operated under a high voltage. Since a regular light emitting diode chip has an operating voltage in the range of 2-4V, it is difficult to operate a single light emitting diode chip under a high voltage. Thus, several light emitting diode chips are connected in series for operation at high voltage. However, using multiple light emitting diode chips results in an increase of the number of wire-bonding processes and an increase of a package size. Further, when the light emitting device is operated under the high voltage, it is necessary for the light emitting device to have a heat dissipation means for handling a large amount of heat generated therefrom and to prevent current leakage caused by application of such high voltage. In particular, when a red light emitting diode chip is used instead of the red phosphor along with a blue light emitting diode chip, a red light emitting diode chip using a compound semiconductor substrate such as GaAs or InP is likely to undergo current leakage through the substrate. The current leakage deteriorates electrical stability, thereby restricting the utility of light emitting diodes.